Light-developable halide emulsions



United States Patent ABSTRACT OF THE DISCLQSURE Light-developable, direct-print silver halide emulsions containing an organic thione halogen acceptor and cornpatible merocyanine spectral sensitizing dyes provide photographic emulsions responsive to wider ranges of radia' tion wavelengths.

This application is a continuation-in-part of U.S. Ser. No. 303,180, filed Aug. 19, 1963, now abandoned.

The present invention relates to photography, and more particularly to light-developable, direct-print photographic silver halide emulsions.

Radiation-sensitive papers adapted for light recording, e.g., oscillographic recording, are well known. Typical of such papers are the developing-out and print-out type. The developing-out type, as the name implies, requires that the exposed material may be chemically developed, fixed and Washed in order to provide a useful visible image on said material. The print-out type of material develops on exposure and requires no development step. The print-out type is generally much slower than the developing-out type and the images are unstable and have a short life.

A third type of radiation-sensitive material especially suitable for light-writing and oscillographic recording comprises a silver halide emulsion layer which, when exposed to a high intensity source of light, forms a latent image which can then be developed by exposure to a second light source of lower intensity. Such direct-writing or direct-printing emulsions are faster than print-out emulsions and require no chemical development. It is this latter type of emulsion that the present invention concerns.

A conventional high intensity light source used in oscillographic recording apparatus to expose photographic products having light-developable, direct-print silver halide emulsions coated thereon is a mercury vapor lamp. Mercury vapor lamps emit light that is rich in ultraviolet light. Silver halide emulsions are inherently sensitive to such light, and thus, there is no necessity to spectrally sensitize silver halide emulsions utilized with such light sources. However, the presence of mercury-containing apparatus is undesirable in confined areas such as in aircraft, submarines, ships and the like because of the toxic nature of mercury as well as its deleterious effect on such metals as aluminum.

Xenon lamps have been found to be particularly useful high intensity light sources for use in oscillographic recording apparatus as a replacement for mercury vapor lamps. Xenon light sources emit light having longer wavelengths than do mercury vapor light sources. Hence, it is desirable to spectrally sensitize silver halide emulsions utilized with apparatus having xenon light sources. However, many halogen acceptors that are utilized in lightdevelopable, direct-print silver halide emulsions reduce the effectiveness of many conventional spectral sensitizing dyes by displacing or desorbing such dyes from the silver halide crystals of the emulsion. Also, many sensitizing dyes impart coloration that persists after photodevelopment when utilized in such products.

It is an object of this invention to provide novel spectrally sensitized light-developable, direct-print silver halide emulsions.

It is another object of this invention to provide novel photographic silver halide emulsions suitable for preparing direct-print recording papers having a high rate of photodevelopment and high stability of the photodeveloped image.

It is another object of this invention to provide novel photographic light-developable, direct-print silver halide emulsions containing spectral sensitizing dyes that bleach out on photodevelopment.

It is still another object of this invention to provide novel photographic 1ight-developable, direct-print silver halide emulsions that can be chemically developed and fixed after photodevelopment to make archival-quality records.

It is likewise an object of this invention to provide new photodevelopable photographic silver halide emulsions that are characterized as having an improved density differential between the initially-exposed and unexposed areas upon photodevelopment.

It is also an object of this invention to provide new photodevelopable photographic silver halide emulsions that have improved resistance in the initially-unexposed areas to density increase upon photodevelopment and subsequent exposure to light.

These and other objects of this invention are accomplished with light-developable, direct-print silver halide emulsions containing an organic thione halogen acceptor and a mercocyanine dye.

A wide variety of organic thiones can be utilized in the light-developable direct-print silver halide emulsions of the invention, including thiols (-SH) or thione compounds that tautomerize to form mercapto radicals e.g.,

s SH H2N(l-NH2 T: H2N(!l=-NH Such compounds have an acidic hydrogen atom attached to a basic sulfur atom. Illustrative types of suitable thiones include thiourea compounds and aromatic thiols.

A particularly useful class of halogen acceptors are the thiourea compounds including thiourea itself and fully or partially substituted thioureas which include the thiourea grouping wherein R is an alkyl or an aryl radical such as those of the naphthyl and phenyl series; and R and R can together he the necessary atoms to complete a heterocyclic nucleus with the thiourea grouping to form such cyclic compounds as an imidazole-thione, an imidazolinethione, a triazine-thiol, a thiobarbituric acid, a thiouracil or the like cyclic compounds and including such substituents as alkyl radicals and aryl radicals such as those of the naphthyl and phenyl series. The alkyl substituents in the described thioureas can be widely varied although alkyls having 1 to 18 carbon atoms are more generally used. The alkyl and aryl radicals of the described thioureas can be substituted or unsubstituted.

Typical suitable thiourea compounds that can be utilized as halogen acceptors in the emulsions of the invention include:

1-methyl-2-imidazolethione 1-n-butyl-1,2,5,6,-tetrahydro-1,3,5-triazine-4-thi0l Thiourea 1-methyl-2-imidazolinethione D-mannose thiosemicarbazone Morpholino-Z-propane thiosemicarbazone D-galactose thiosemicarbazone l,3-dimethyl-Z-imidazolinethione Z-imidazolinethiOne 1-phenyl-S-mercaptotetrazole Thiosemicarbazide Tetramethylthiourea p-Dimethylaminobenzaldehyde-thiosemicarbazone l-isopentyl-Z-thiourea 1-(2-diethylaminoethyl)-1,2,5,6-tetrahydro-1,3,5-triazine- 4-thiol 1,2-bis( 1,2,5 ,6-tetrahydro-1,3,5-triazine-4-thiol ethane l-phenyl-Z-thiourea 1,3-diphenyl-2-thiourea 4-thiobarbituric acid 2-thiouraci1 l-acetyl-Z-thiourea 1,3-dibenzyl-2-thiourea 1,1-diphenyl-2-thiourea l-ethyl-l-(a-naphthyl)-2-thiourea Z-imidazolethione l-phenyl-2-irnidazolinethione 4,5-diphenyl-2-imidazolinethione 1- (o-rnethoxyphenyl) -2-thiourea Thiosalicylic acid,

:p-Toluenethiol,

Benzenethiol,

Z-naphthalenethiol, and the like aromatic thiols.

The concentration of halogen acceptor utilized in the a emulsions of the invention can be widely varied in accordance With usual practice. Generally, about .01 to 25 mole percent, and preferably about .1 to 5 mole percent, based on the silver halide in the emulsion is utilized.

The merocyanine optical sensitizing dyes utilized in the emulsions of the invention have the formula wherein: X can be a sulfur or a selenium atom; R can be an alkyl radical, an aryl radical such as phenyl or a hydrogen atom; Y can be an oxygen atom, a sulfur atom, a selenium atom,

I fll) wherein R can be the same substituents as R and wherein R can be the same substituents as J; n is an integer of O to 2; R and R are hydrogen atoms, lower azoline, a pseudoindole and the like. The Y substituent is preferably I gm to form a thiohydantoin nucleus. When Y is a sulfur atom, the heterocyclic moiety completed by the substituent, Z, is other than thiazoline. At least one of the substituents R", R or R is preferably a higher alkyl radical or a hydrogen atom when such thiourea halogen acceptors as triazine-4-thiols (e.g., 1-I1-butyl-l,2,5,6-tetrahydro-1,3,5-triazine-4-thiol) are used. The alkyl substituents in the described merocyanine dyes can be widely varied although alkyls having 1 to 18 carbon atoms are more generally used, those alkyls denominated lower alkyls having 1 to 4 carbon atoms and those alkyls denominated higher alkyls having 5 to 18 and preferably 7 to 18 carbon atoms. The alkyl and aryl radicals of the described dyes can be substituted or unsubstituted. Typical suitable merocyanine dyes used to spectrally sensitize the emulsions of the invention include:

5-[ (3-ethyl-2-benzothiazolinylidene) ethylidene] rhodanine 5 (3 -ethyl-2-benzothiazolinylidene) ethylidene] -2-thio- 2,4-oxazolidinedione 5-[ (3 -ethyl-2-benzothiazolinylidene)ethylidene]-3-hepty1- l-phenyl-Z-thiohydantoin 5-[l-ethylnaphtho{1,2-d}thiazolin-2-y1idene)ethylidene]- 3 -n-heptyl-1-phenyl-2-thiohydantoin 5 (3 -ethyl-2-b enzothiazolinylidene ethylidene] -2-thiohyd antoin 5-[ (3 -ethylnaphth{2, l-d} oxazolin-Z-ylidene ethylidene] 3 -n-heptyll-phenyl-Z-thiohydantoin 5 (3-ethyl-Z-benzoxazolinylidene ethylidene] -4-thiohydantoin 3 -ethyl-5-[ (3-ethyl-2-benzothiazolinylidene ethylidene] Z-thiohydantoin 5- [di( 3-et1hyl-2-benzothiazolinylidene)isopropylidene] .1-rnethyl-2-tliiobarbituric acid 5- [di 3-ethyl-2-benzothiazolinylidene isopropylidene Z-thiobarbituric acid 5- [4- 3 -ethyl-2-benzothiazolinylidene -2-butenylidene] 3-n-heptyl-1+phenyl-2-thiohydantoin 5- (3 -ethyl-5-ph enyl-4-oXazolin-2-ylidene ethylidene] 3 -heptyl-1-phenyl-Z-thio-hydantoin l-rnethyl-5-[ 1,3,3-trimethyl-Z-indolinylidene) ethylidene]-Z-thiobarbituric acid 5-(3-ethyl-2-benzothiazolinylidene)-3-heptyl-1-phenyl-2- thiohydantoin 3 -ethy1-5 3 -ethyl-2-benzoxazolinylidene) isopropylidene] -2-thio-2,4-oxazolidinedione 5- (3-ethyl-Z-benzothiazolinylidene) ethylidene] -1-phenyl- Z-thiobarbituric-acid 5-[ (3-ethyln aphth{2, l-d} oxazolin-Z-ylidene) iso-propylidene -3 -heptylrhod anine 1-ethyl-5-[ (1-ethylnaphtho{1,Z-d}thiazolin-Z-ylidene) isopropylidene] -2-thiobarbituric acid 5 1 -ethyl-2 l H) -quinolylidcne) ethylidene] -3-lauryl-2- thio-2,4-oxazolidinedione 1-rnethyl-5-[ (3-methy1-2-thiazolidinylidene) ethylidene Z-thiob arbituric acid 5 [4- 3-methyl-2-b enzoxazolinylidene) l ,3-neopentylene- Z-butenylidcne] -2-thiobarbituric acid 5-[ (3 -ethyl-2-benzoselenazol i nylidene) ethylidene] -3- heptyl-Z-thiohydantoin 5 3 1,2-dihydropyrrolo 2, 1d}benzothiazolyl) methylene] -3-heptyl-l-phenyl-Z-thiohydantoin 5-[(5,6-dichloro-1,3-diethy1-2-benzimidazolinylidene)- ethylidene1- 1-ethy1-2-thiobarbituric acid 5 (3 -ethyl-,2-benzothiazolinylidene ethylidene] -3-heptyl- 2-seleno-2,4-thiazolidinedione 5-[ (3 -ethyl-2-benzothiazolinylidene) ethylidene1-3 -heptyl- 2-thio-2,4-selenazolidinedione 5-[ (3-ethyl-2-benzothiazolinylidene)ethylidene1-3-heptylrhodanine 5- (3 -ethyl-2-benzothiazolinylidene) ethylidene] -3 -laurylrhodanine 5 3-ethyl-2-benzoxazolinylidene) ethylidene] -3-decyl- 1 -phenyl-2thiohydantoi.u

5-[ (3-ethyl-2-benzoxazolinylidene) ethylidene]-1 hepty1 3-phenyl-2-thiohydantoin 3-heptyl-5- 1-rnethylnaphtho{1,2-d}thiazolin-Z-ylidene)- l-phenyl-Z-thiohyd antoin The sensitizing amount of sensitizing dyes utilized can be widely varied. The concentration of the dyes will vary according to the type of emulsion and according to the effect desired. The suitable and most economical concentration for any given emulsion will be apparent to those skilled in the art upon making the ordinary tests and observations customarily used in the art of emulsion making. Generally about to 1000 mg. of dye per mole of silver halide in the emulsion are utilized. About .05 to 1 mole percent of sensitizing dye based on the silver halide in the emulsion is a typical working range. A single merocyanine dye or combinations of several merocyanine dyes can be used in the present emulsions for spectral sensitization.

At least one water-soluble halide in an amount sufficient to provide an excess of halide ions over that necessary initially to precipitate all of the silver as silver halide in the preparation thereof is desirably utilized. More generally, at least about .05 mole percent, and usually about .05 to 10 mole percent, based on the silver halide in the emulsion is utilized. Water-soluble iodides are particularly useful. Illustrative water-soluble halides include ammonium, calcium, lithium, magnesium, potassium, or sodium bromide, chloride or iodide.

A wide variety of light-developable, direct-print photographic silver halide emulsions can be utilized in the pres ent invention, such being well known to those skilled in the present art. Suitable silver halides include silver chloride, silver bromide, silver bronioiodide, silver chloroiodide, and silver chlorobromoiodide. For a description of suitable emulsions, reference is made to Davey et al., US. Patent 2,592,250, issued Apr. 8, 1952; Glafkides, Photographic Chemistry, vol. 1, pp. 31-2, Fountain Press, London; and McBride application Ser. No. 222,964, filed Sept. 11, 1962, wherein is disclosed the preparation of silver halide emulsions with organic thioether silver halide solvents present during the grain growth of the silver halide. McBride teaches that the thioether silver halide solvent can be added to the colloidal material in which the silver halide is precipitated, during the precipitation of the silver halide or to the silver halide prior to or during the ripening of the silver halide. Typical of such thioethers include 3,6-dithia-1,8-octanediol, 1,10'dit'hia-4,7, 13,1G-tetraoxacyclooctadecane, 7,10-diaza-l,l6-diczurboxamide-3,l4-dithiahexadecane-6,1l-dione, and 1,17-di-(N- ethylcarbaimyl) 6,12 dithia 9 oxaheptadecane. The amount of thioether utilized to prepare the silver halide emulsions described by McBride can *be widely varied although about .1 to 25 g. of thioether per mole of silver halide is generally utilized. The present silver halide emulsions generally have an average grain size of about .1 to 10 microns, and more generally about .5 to 1 micron. Water-soluble lead salts are preferably present during the grain growth of the silver halide to form silver lead halide grains which preferably contain about .01 to 5 mole percent lead based on the silver.

The so-called internal image emulsions are particularly useful in the invention, such emulsions are prepared with silver halide grains wherein a substantial amount, and preferably a predominant amount, of the sensitivity to radiation is internal to the grains. Typically, such internal image emulsions are those which, when measured according to normal photographic techniques by coating a test portion of the emulsion on a transparent support, exposing to a light intensity scale having a fixed time between 1X10 and 1 second, bleaching 5 minutes in a 0.3% potassium ferricyanide solution at 65 F. and developing for about 5 minutes at 65 F. in Developer B below (an internal-type developer), have a sensitivity, measured at a density of 0.1 above fog, greater than the sensitivity of an identical test portion which has been exposed in the same way and developed for 6 minutes at 68 F. in Developer A below (a surface-type developer).

DEVELOPER A G. N-methyl-p-aminophenol sulfate 0.31 Sodium sulfite, desiccated 39.6 Hydroquinone 6.0 Sodium carbonate, desiccated 18.7 Potassium bromide 0.86 Citric acid 0.68 Potassium metabisulfite 1.6 Water to make 1 liter.

DEVELOPER B N-methyl-paminophenol sulfate 2.0 Sodium sulfite, desiccated 90.0 Hydroquinone 8.0 Sodium carbonate, monohydrate 52.5 Potassium bromide 5.0 Sodium thiosulfate 10.0

Water to make 1 liter.

A wide variety of hydrophilic, water-permeable organic colloids can be suitably utilized in preparing the silver halide emulsions or dispersions of the invention. Gelatin is preferably utilized although other colloidal materials such as colloidal albumin, cellulose derivatives, synthetic resins or the like can be utilized. Suitable colloids that can be used are polyvinyl alcohol or a hydrolyzed polyvinyl acetate as described in Lowe US. Patent 2,286,215, issued June 16, 1942; a far hydrolyzed cellulose ester such as cellulose acetate hydrolyzed to an acetyl content of 19-26% as described in US. Patent 2,327,808 of Lowe and Clark, issued Aug. 24, 1943; a water-soluble ethanolamine cellulose acetate as described in fully US. Patent 2,322,085, issued June 15, 1943; a polyacrylamide having a combined acrylamide content of 30 to 60% and a specific viscosity of 0.25 to 1.5 on an imidized polyacrylamide of like acrylamide content and viscosity as described in Lowe, Minsk and Kenyon US. Patent 2,541,- 474, issued Feb. 13, 1951; zein as described in Lowe US. Patent 2,563,791, issued Aug. 7, 1951; a vinyl alcohol polymer containing urethane carboxylic acid groups of the type described in Unruh and Smith US. Patent 2,768,154, issued Oct. 23, 1956; or containing cyanoacetyl groups such as the vinyl alcohol-vinyl cyanoacetate copolymer as described in Unrdh, Smith and Priest US. Patent 2,808,331, issued Oct. 1, 1957; or a polymeric material which results from polymerizing a protein or a saturated acylated protein with a monomer having a vinyl group as described in Illingsworth, Dann and Gates US. Patent 2,852,382, issued Sept. 19, 1958.

The subject photodevelopable photographic silver halide emulsions of the invention can contain the addenda generally utilized in such products including gelatin hardeners, gelatin plasticizers, coating aids and the like.

The above-described emulsions of the invention can be coated on a wide variety of supports in accordance with usual practice. Typical supports for photographic elements of the invention include paper, cellulose nitrate film, cellulose acetate film, polyvinyl acetal film, polystyrene film, polyethyleneterephthalate film, polyethylenecoated paper, and related films of resinous materials and others.

In forming a photodeveloped image with a typical photographic element having coated thereon an emulsion of the invention, the emulsion on the element is initially exposed to a high intensity light source to form a latent image in the emulsion, and thereafter the resulting latent image is photodeveloped by exposing it to a light source of less intensity than the original exposure. A typical instrument for exposing the emulsion of the invention is an oscillogr-aph of the type described by Heiland in US. Patent 2,580,427, issued Jan. 1, 1952. Typical suitable high intensity light sources are mercury vapor lamps that have high blue and ultraviolet emission, xenon lamps that emit light of wavelengths similar to daylight, and tungsten lamps that have high red light emission. The low intensity light source that is utilized to effect the photodevelopment after the high intensity exposure can be conventional fluorescent light, a tungsten light or even ordinary daylight.

While the present merocyanine spectral sensitizing dyes in the emulsions of the invention impart coloration or stain to such emulsions prior to exposure and photode velopment, such stain is substantially bleached or made colorless during the photodevelopment step. When conventional cyanine dyes are substituted for the present merocyanine dyes in light-developable, direct-print emulsions, the stain of the dye persists after photodevelopment as objectionable background coloration in the nonimage or D areas.

After exposure and photodevelopment, certain of the emulsions of the invention containing the subject mer captan halogen acceptors can be chemically developed and fixed to make archival-quality records if desired. Emulsions of the invention containing halogen acceptors like stannous salts (e.g., stannous chloride) cannot be so readily developed and fixed as such halogen acceptors tend to cause fog during such a chemical processing.

The invention is further illustrated by the following examples of preferred examples thereof.

Example 1 A light-developable, direct-print, light-sensitive gelatino-silver chlorobromide emulsion (95% bromide, 5% chloride) having silver halide grains of high internal sensitivity was prepared by slowly adding an aqueous solution of silver nitrate containing .85 g. of lead nitrate per mole of silver to an aqueous gelatin solution containing a stoichiometric excess of potassium chloride and potassium bromide to provide a large-grain emulsion, .5 g. of 1,8-dihydroxy-3,6-dithiaoctane per mole of silver being added during the silver halide precipitation. The emulsion was washed with water to remove water-soluble salts. The prepared emulsion was divided up into several portions and to each portion of the emulsion was added a spectral sensitizing dye in acetone or methanol at a concentration of 120 mg. per mole of silver halide, 400 mg. of 1 n butyl-l,2,5,6-tetrahydro-1,3,5-triazine-4- thiol in methanol per mole of silver halide and 1.6 grams of potassium iodide per mole of silver halide. The resulting emulsions were coated on paper supports at a silver coverage of 260 mg. per square foot and at a gelatin coverage of 560 mg. per Square foot. Strips of each coating containing various spectral sensitizing dyes were exposed on an Edgerton, Germeshausen and Grier Mark VII sensitometer containing a xenon flash lamp for microseconds through a 0.15 log E density-increment neutral density step tablet followed by a photodevelopment of 5 minutes with a 60 foot-candle cool white fluorescent light. Table I below summarizes the number of 0.15 log neutral density steps for the various dyes utilized in the test, this giving indication of overall white light speed. Other portions of the various test coatings were also exposed through the described step tablets containing a yellow filter (Wratten No. 16) to filter out blue light. This latter test indicated the speed to minus blue light and the effect of the optical sensitizing dye. The number of 0.15 log E minus blue steps is also summarized by the data set out in Table I below.

TABLE I Minus Blue White In Table I above, the designated optical sensitizer dyes are as set out below, dyes a to e being merocyanine dyes used in the emulsions of the invention and dyes f and g being cyanine dyes.

(a) 5- (3-ethyl-2-benzothiazolinylidene ethylidene] rhoadnine (b) 5- (3-ethyl-2-benzothiazolinylidene ethylidene] -2- thio-2,4-oxazolidinedione (c) 5- (3-ethyl-2-benzothiazolinylidene ethylidene] -3- heptyl-1-phenyl-2-thiohydantoin (d) 5- l-ethylnaphtho{1,2-d}thiazolin-2-ylidene) ethylidene] 3-n-heptyll-phenyl-Z-thiohydantoin (e) 5 (3-ethyl-2-benzothiazolinylidene ethylidene]-2- thiohydantoin (f) 3,3-9-triethyl-5,5'-diphenyloxacarbocyanine iodide (g) 9-ethyl-3,3'-di(B-methoxyethyl)-5,5-diphenyloxacar bocyanine iodide.

As can be observed from the data set out in Table I above, the merocyanine dyes utilized in the emulsions of the invention (Dyes a to e) effectively sensitive the subject direct-print emulsions to light having wavelengths greater than blue light while the cyanine dyes f and g do not effectively sensitize the emulsions to light of such longer wavelengths. After the photodevelopment of the emulsions containing dyes a to e of the invention, the dyes in the respective samples faded in the background or D areas while the samples containing dyes f and g retained a dye stain in the background or non-image areas. Suitable light-developable, direct-print gelatinosilver halide emulsions to which the feature addenda can be added can also be prepared by the method of Davey et al., U.S. Patent 2,592,250, issued Apr. 8, 1952.

Example 2 Several light-developable, direct-print, light-sensitive, gelatino-silver chlorobromide emulsions of the type described in Example 1 were prepared and exposed as described in Example 1 except that the dyes were utilized at a concentration of 133 mg. per mole of silver halide and the potassium iodide was utilized at a concentration of 0.83 gram per mole of silver halide. The results of the tests were summarized by the data set out in Table II below.

TABLE II Visible 0.15 log E Steps on Exposure and Photodevelopment Dye Minus Blue White co wcovowenwo HHHHFD-H ocooquuooq In Table II above, dye a is described in Example 1 and dyes h to n are identified below, dyes in and n. being dyes not used in the invention included for comparative purposes.

(it) 3-ethylnaphth{2, 1-d}oxazolin-2-ylidene ethylidene]-3-n-heptyl-l-phenyl-2-thiohydantoin i) 5 3-ethyl-2-b enzoxazolinylidene) ethylidene]-4- thiohydantoin (j) 3-ethyl-5-[ 3-ethyl-2-benzothiazolinylidene) ethylideneJ-Z-thiohydantoin (k) 5-[di(3-ethyl-2-'benzothiazolinylidene)isopropylidene]-l-methyl-2-thiobarbituric acid l 5- [di 3-ethyl-2-benzothiazolinylidene) isopropylidene1-2-thiobarbituric acid (m) 2- Z-benzothiazolyl imino-3-ethyl-5-[4- 3 -ethyl2- benzothiazolinylidene) 1,3-neopentylene-2-butenylideneJ-4-thiazolidinone (n) 2-{ l- (Z-benzothiazolyl)-3-methyl-5-oxo-2-pyrazolin-4-ylidene] ethylidene}-3-ethyl-5- (3-ethyl-2-benzoxazolinylidene) ethylidene] -l-phenyl4-imidaz0lidinone.

As can be observed from the data set out in Table II above, the direct-print emulsions of the invention containing dyes a and h to l Were effectively spe-ctrally sensitized. However, closely-related dyes in and It did not spectrally sensitize the silver halide emulsions.

Example 3 Several light-developable, direct-point, light-sensitive, gelatino-silver chlorobromide emulsions of the type described in Example 1 were prepared and exposed as described in Example 1 except that various thiourea halogen acceptors were substituted for the l-n-butyl-1,2,5,6- tetrahydro-1,3,5-triazine-4-thiol halogen acceptor. Dye (I described in Example 1 was utilized at a concentration of 120 mg. per mole of silver halide as the spectral sensitizing dye, the various halogen acceptors were used at a concentration of 0.12 mole percent based on the silver halide and the potassium iodide was utilized at a concentration of 1.65 grams per mole of silver halide. The various coatings were exposed as described in Example 1. Results of the tests are summarized by the data set out in Table III below. In addition to the tests described in Example 1, other test portions were exposed to D and the whole strip photodeveloped 5 minutes with a 60 foot-candle cool white fluorescent light. The density in the exposed and unexposed areas was read through a Wratten No. 15 filter on a curve-tracing densitometer and the difference recorded as AD for 300 foot-candleminutes of photodevelopment. This latter determined value is also set out in Table III below.

TABLE III Visible 0.15 log E Steps on Exposure and Photodevelopment 300 fem. Thiourea Compound AD Minus Blue White I 15 21 .38 II i. 14 21 37 III r 14 21 67 IV 15 21 .36

The designated thiourea compounds of Table III above are identified below.

I. Z-imidazolinethione II. l-methyl-2-imidazolethione III. 1-metl1yl-2-imidazolinethione IV. l,3-dimethyl-2-imidazolinethione Example 4 A light-developable, direct-print, light-sensitive gelatino-siiver chlorobromide emulsion bromide, 5% chloride) was prepared by the general method described in Example 1. To various samples of the emulsions Were added various sensitizing dyes at a concentration of mg. of dye per mole of silver halide, 1.66 grams of potassium iodide per mole of silver halide, and a thiourea halogen acceptor at a concentration of 400 mg. per mole of silver halide. The various emulsions were coated at a coverage of 258 mg. of silver per square foot and 560 mg. of gelatin per square foot on photographic paper supports. The various coatings were thereafter exposed as described in Example 3 and the number of visible 0.15 log E steps obtained when exposed through a yellow filter were observed as well as the differences in density between the D and D areas and the amount of residual dye stain after photodevelopment were observed and recorded in Table IV below.

TABLE IV Visible 0.15 log E Stops On Exposure and Photo- 'Ihiourea development 300 Lem. D ye Compound an AD Stain Dye Minus Blue 0 38 10 .35 Low. 10 36 Low. 7 43 Low. 3 42 Low. 1 38 High. 0 .39 13 40 Low. 13 40 Low. 13 39 Low.

In Table IV, the dyes not previously identified in other examples are:

(p 3-n-l1eptyl-5 (3-methyl-2-thiazolidinylidene) ethylideneJrhodanine q) 5- 3-etl1yl-2-benzothiazolidinylidene ethylidene] rhoclanine (r) 5-[ (3-ethyl-2-benzothiazolinylidene)ethylidene]-2- thio-2,4-oxazolidinedione (s) l,3-diethylselena-2-cyanine iodide.

In Table IV the thiourea compounds are:

V. 1-n-butyl-l,2,5,6-tetrahydro-1,3,5-triazine4-thio1 VI. thiourea As can be observed from the data set out in Table IV above, the direct-print emulsions of the invention containing thiourea compounds plus certain specific merocyanine dyes, namely, dyes r, q, d and p resulted in sensitization of the emulsion to minus blue light as Well as producing a product having low residual dye stain. HOW- ever, sensitzing dye .9 did not impart substantial sensitization to minus blue light to the subject emulsions containing thiourea compounds, and in addition, dye s left a high residual dye stain on the photodeveloped product.

Example A .light-developable, direct-print, light-sensitive gelatino-silver chlorobromide emulsion (95% bromide, 5% chloride) was prepared by the general method described in Example 1 except that 2 g. of 1,10-dithia-4,7,13,16- tetraoxacyclooctadecane per mole of silver halide was added during the precipitation of the silver halide. Into test portions of the emulsion were incorporated the spectral sensitizing dye, dye c described in Example 1, in methanol at concentrations of .05 and .10 gram of dye per mole of silver halide and the halogen acceptor, thio salicyclic acid, in methanol at a concentration of 2.2 grams per mole of silver halide. For purposes of comparison dye t, anhydro-9-methyl-3,3'-di(3-sulf0butyl) thiacarbocyanine hydroxide, was substituted for dye c. The emulsions were coated on paper supports at silver coverages of 257 mg. per square foot and at gelatin coverages of 560 mg. per square foot. The coatings were exposed to a high intensity xenon flash in a sensitometer for 500 microseconds through a 0.15 log E neutral density step tablet and a yellow filter (Wratten N0. 16) and thereafter :photodeveloped by exposing to two l5-watt cool white fluorescent lights at a distance of 6 inches for about one minute. The number of visible minus blue light 0.15 log E steps obtained is summarized in Table V below. A control emulsion containing no spectral sensitizing dye was also included for purposes of comparison.

As can be noted from the data set out in Table V, the merocyanine dye, dye c, spectrally sensitized the silver halide emulsion in the presence of the thiosalicylic acid halogen acceptor, while the carbocyanine dye was ineffective. Results similar to those obtained with dye c were also obtained when dye u, 3-ethyl-5-[(3-ethyl-2-benzoxazolinylidene)isopropylidene] 2thio 2,4 oxazolidinedione, was substituted for dye c at the same concentration level.

Thus, the present invention provides novel and useful light-developable, direct-print silver halide emulsions containing a halogen acceptor that can be effectively spectrally sensitized. We have found a narrow class of merocyanine dyes that can be effectively utilized in combination with a wide variety of halogen acceptors, and which merocyanine dyes have particular utility with halogen acceptors that displace or desorb spectral sensitizing dyes from silver halide grains.

The invention has been described in considerable detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

I claim:

1. A light-developable, direct-print silver halide emulsion containing at least about .01 mole percent of an organic thione halogen acceptor per mole of silver halide 12. and a merocyanine spectral sensitizing dye having the formula wherein:

(A) R", R and R are each selected from the group consisting of (1) an alkyl radical, (2) an aryl radical, and (3) a hydrogen atom;

(B) X is selected from the group consisting of (1) a sulfur atom, and (2) a selenium atom;

(C) Y is selected from the group consisting of (1) an oxygen atom, (2) a sulfur atom, (3) a selenium atom, (4) a group having the formula wherein R can be the substituents of R and (5) a group having the formula wherein R can be the substituents of R (D) n is an integer of 0 to 2; (E) R is selected from the group consisting of (1) an alkyl radical, and (2) an aryl radical; and (F) Z represents the atoms required to complete a basic heterocyclic nucleus, Z being other than the atoms required to complete a thiazoline nucleus when Y is a sulfur atom.

2. A light-developable, direct-print silver halide emulsion containing at least about 0.1 mole percent of a thiourea halogen acceptor per mole of silver halide having the formula 2 1 III wherein:

(A) R and R are each selected from the group consisting of (1) a hydrogen atom,

(2) an acyl radical,

(3) a nitrogen-containing radical having a formula selected from the group consisting of -NH and -N CHR wherein R is selected from the group consisting of an alkyl radical and an acyl radical,

(4) an alkyl radical, and

(5) an aryl radical;

(B) R and R are each selected from the group consisting of (1) a hydrogen atom,

(2) an acyl radical,

(3) a nitrogen-containing radical having a formula selected from the group consisting of -NH and -N=CH-R wherein R is selected from the group consisting of an alkyl radical and an acyl radical,

(4) an alkyl group,

(5) an aryl group, and

(6) together the necessary atoms to complete a heterocyclic nucleus;

from the group wherein R can be the substituents of R and a group having the formula wherein R can be the substituents of R (D) n is an integer of 0 to 2; (E) R is selected from the group consisting of 1) an alkyl radical, and (2) an aryl radical; and (F) Z represents the atoms required to complete a basic heterocyclic nucleus, Z being other than the atoms required to complete a thiazoline nucleus when Y is a sulfur atom.

3. A light-developable, direct-print silver halide emulsion as described in claim 2 prepared with an organic thioether silver halide solvent present during the grain growth of the silver halide.

4. A light-developable, direct-print silver halide emulsion as described in claim 2 that contains a water-soluble iodide.

5. A light-developable, direct-print silver halide emulsion containing at least about .01 mole percent of an aromatic thione halogen acceptor per mole of silver halide and a merocyanine spectral sensitizing dye having the formula from the group 14 (4) a group having the formula wherein R can be the substituents of R", and (5) a group having the formula 0 R Ill wherein R can be the substituents of R (D) a is an integer of 0 to 2;

(E) R is selected from the group consisting of 1) an alkyl radical, and (2) an aryl radical; and (F) Z represents the atoms required to complete a basic heterocyclic nucleus, Z being other than the atoms required to complete a thiazoline nucleus when Y is a sulfur atom.

6. A light-developable, direct-print silver halide emulsion as described in claim 5 prepared with an organic thioether silver halide solvent present during the grain growth of the silver halide.

7. A light-developable, direct-print silver halide emulsion as described in claim 5 that contains a water-soluble iodide.

8. A light-developable, direct-print silver halide emulsion containing at least about 0.1 mole percent of a triazine-4-thiol halogen acceptor per mole of silver halide, and a merocyanine spectral sensitizing dye having the formula- :t ax Y wherein R can be the substituents of R and (5) a group having the formula 0 R" g l N wherein R can be the substituents of R; (D) n is an integer of O to 2; (E) R is selected from the group consisting of (1) an alkyl radical, and (2) an aryl radical; and (F) Z represents the atoms required to complete a basic heterocyclic nucleus, Z being other than the atoms required to complete a thiazoline nucleus when Y is a sulfur atom.

' 9. A light-developable, direct-print silver halide emulsion as described in claim 8 wherein the triazinel-thiol is l-n-butyl-1,2,5,6-tetrahydro-1,3,5-triazine-4-thiol.

10. A light-developable, direct-print silver halide emulsion containing at least about .01 mole percent of a 2- imidazolethione halogen acceptor per mole of silver halide, and a merocyanine spectral sensitizing dye having the formula wherein:

(A) R' R and R are each selected from the group consisting of (1) an alkyl radical, (2) an aryl radical, and (3) a hydrogen atom; (B) X is selected from the group consisting of (1) a sulfur atom, and (2) a selenium atom; (C) Y is selected from the group consisting of (1) an oxygen atom, (2) a sulfur atom, (3) a selenium atom, (4) a group having the formula R10 1 wherein R can be the substituents of R and (5 a group having the formula o E" II l C N wherein R can be the substituents of R"; (D) n is an integer of to 2; (E) R is selected from the group consisting of (1) an alkyl radical, and (2) an aryl radical; and (F) Z represents the atoms required to complete a basic heterocyclic nucleus, Z being other than the atoms required to complete a thiazoline nucleus When Y is a sulfur atom.

11. A light-developable, direct-print silver halide emulsion as described in claim 10 wherein the Z-imidazolethione is 1-methyl-2-imidazolethione.

12. A light-developable, direct-print silver halide emulsion containing at least about .01 mole percent of the thione halogen acceptor, 2-i1nidazolinethione, per mole of silver halide, and la merocyanine spectral sensitizing dye having the formula wherein:

(A) R, R and R are each selected from the group consisting of (1) an alkyl radical, (2) a aryl radical, and (3 a hydrogen atom; (B) X is selected from the group consisting of 1) a sulfur atom, and (2) a selenium atom; (C) Y is selected from the group consisting of (1) an oxygen atom, (2) a sulfur atom,

(3) a selenium atom, (4) a group having the formula wherein R can be the substituents of R and a group having the formula wherein R can be the substituents of R";

lb? (D) n is an integer of 0 to 2; (E) R is selected from the group consisting of (1) an alkyl radical, and (2) an aryl radical; and (F) Z represents the atoms required to complete a basic heterocyclic nucleus, Z being other than the atoms required to complete a thiazoline nucleus when Y is a sulfur atom.

13. A light-developable, direct-print silver halide emulsion as described in claim 12 wherein the thione halogen acceptor is Z-imidazolinethione.

14. A light-developable, direct-print silver halide emulsion containing at least about .01 mole percent thiourea per mole of silver halide as a halogen acceptor, and a merocyanine spectral sensitizing dye having the formula o n H I wherein R can be the substituents of R";

(D) n is an integer of 0 to 2;

(E) R is selected from the group consisting of (1) an alkyl radical, and (2) an aryl radical; and (F) Z represents the atoms required to complete a basic heterocyclic nucleus, Z being other than the atoms required to complete a thiazoline nucleus when Y is a sulfur atom.

15. A light-developable, direct-print silver halide emulsion containing at least about .01 mole percent thiosalicylic acid per mole of silver halide as a halogen acceptor and a merocyanine spectral sensitizing dye having the formula wherein:

(A) R R and R are each selected from the group consisting of (1) an alkyl radical, (2) an aryl radical, and (3) a hydrogen atom;

(B) X is selected from the group consisting of (l) a sulfur atom, and (2) a selenium atom;

(C) Y is selected from the group consisting of (1) an oxygen atom, (2) a sulfur atom, (3) a selenium atom, (4) a group having the formula wherein R can be the substituents of R and (5) a group having the formula R H l U N wherein R can be the substituents of R (D) n is an integer of 0 to 2; (E) R is selected from the group consisting of (1) an alkyl radical, and (2) an aryl radical; and (F) Z represents the atoms required to complete a basic heterocyclic nucleus, Z being other than the atoms required to complete a thiazoline nucleus when Y is a sulfur atom.

16. A light-developable, direct-print silver halide emulsion containing at least about .01 mole percent of a thiourea halogen acceptor per mole of silver halide having the formula r t R NL, NR wherein:

(A) R and R are each selected from the group consisting of (1) a hydrogen atom,

(2) an acyl radical,

(3) a nitrogen-containing radical having a formula selected from the group consisting of NH and -N=CHR wherein R is selected from the group consisting of an alkyl radical and an acyl radical,

(4) an alkyl radical, and

(5) an aryl radical;

(B) R and R are each selected from the group consisting of (l) a hydrogen atom,

(2) an acyl radical,

(3) a nitrogen-containing radical having a formula selected from the group consisting of -NH and N=CH-R wherein R is selected from the group consisting of an alkyl radical and an acyl radical;

(4) an alkyl radical,

(5) an aryl radical, and

(6) together the necessary, atoms to complete a heterocyclic nucleus;

and a merocyanine spectral sensitizing dye having the formula .2. 0=o--N-R b(=oHoH ..=o C =S t. t.

wherein:

(A) R and R sisting of 1) a hydrogen atom,

(2) an alkyl radical, and

(3) a phenyl radical;

are each selected from the group con- 18 (B) n is an integer of 0 to 2; (C) R is selected from the group consisting of (1) an alkyl group, and (2) a phenyl group; and

(D) Z represents the necessary atoms to complete a heterocyclic basic nucleus.

17. A light-developahle, direct priut gelatinosilver halide emulsion comprising silver halide grains having a substantial amount of sensitivity internal to said grains, about .01 to 25 mole percent based on said silver halide of thiourea, about 10 to 1000 mg. per mole of said silver halide of 5-[(3ethyl-2 benzothiazolinylidene)ethylidene] rhodanine, and about .05 to 10 mole percent based on said silver halide of potassium iodide.

iii. A light-developable, direct-print, gelatino-silver halide emulsion comprising silver halide grains having a substantial amount or sensitivity internal to said grains, about .01 to 25 mole percent based on said silver halide of Z-imidazoline-thione, about 10 to 1000 mg. per mole of said silver halide of 5[(3--ethyl-2-benzothiazolinylidene)ethylidene] 3-nheptyl-lphenyl-Zhydantoin, and about .05 to 10 mole percent based on said silver halide of potassium iodide.

19. A light-developable, direct print gelatino silver halide emulsion comprising silver halide grains having a substantial amount of sensitivity internal to said grains, about .01 to 25 mole percent based on said silver halide of l-n-butyl-l,2,5,6-tetrahydro--1,3,5-triazine-4-thiol, about 10 to 1000 mg. per mole of said silver halide of 5-[(1-ethylnaphtho{1,2 d}thiazolin 2 ylidene)ethylidene] 3-nheptyl-1-phenyl-2--thiohydautoin, and about .05 to 10 mole percent based on said silver halide of potassium iodide.

20. A light-developable, direct-print gelatino-silver halide emulsion comprising silver halide grains having a substantial amount of sensitivity internal to said grains, about .01 to 25 mole percent based on said silver halide of 1-methyl-2-imidazole-thione, about 10 to 1000 mg. per mole of said silver halide of 5-[(l-ethylnaphtho{l,2-d}thiazolin-Z-ylideue)ethylidene] -3-n-heptyl-l-phenyl 2 thiohydantoin, and about .05 to 10 mole percent based on said silver halide of potassium iodide.

21. A ligh -developable, direct-print gelatino-silver halide emulsion comprising silver halide grains having a substantial amount of sensitivity internal to said grains, about .01 to 25 mole percent based on said silver halide of thiosalicylic acid about 10 to mg. per mole of said silver halide of 5-[(1 ethylnaphtho{1,2 d}thiazolin-2- ylidene)ethylidene] 3-n-heptyl 1 phenyl-2-thiohydantoin, and about .05 to 10 mole percent based on said silver halide of potassium iodide.

References Qited UNITED STATES PATENTS 3,163,536 12/1964 Nishio et al 96-107 3,271,157 9/1966 McBride 96-107 3,287,136 11/1966 McBride 96-106 NORMAN G. TORCHIN, Primary Examiner. J. TRAVIS BROWN, Examiner. J. H. RAUBITSCHEK, Amislant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,364,032 January 16, 1968 Jean E. Jones It is hereby certified that error appears in the above numbered pat ent. requiring correction and that the said Letters Patent should read as corrected below.

Column 13, lines 4 to 8, the formula should appear as shown elow instead of as in the patent:

I g fff? N, R R n Y column 18, line 21, for "3-n-" read 3-nline 30, for 1,2-d" read 1,2-d same line 30, for "-3n" read 3-nline 38 for "1 ,2-d" read 1 ,2-d line 39 for "3-n-" read 3-nline 46 for 100" read 1000 line 47 for "1 ,Z-d" read 1 ,2-d line 48 for "-3-n-" read 3-n Signed and sealed this 22nd day of July 1969.

(SEAL) Attest z EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, JR. Attesting Officer I Commissioner of Patents 

